In engine design there may be trade-offs between strength, weight, and other material properties of materials used to construct the cylinder head and block. For example, iron has been used to manufacture cylinder blocks. Cast iron may have several benefits over other materials, such as a smaller volume to strength ratio and a smaller friction coefficient, decreasing the engine's size and increasing combustion chamber longevity. However, cast iron cylinder blocks may have a low strength to weight ratio, are more susceptible to corrosion, and have undesirable heat transfer characteristics. To reduce block weight and increase the amount of heat transferred to water jackets, cylinder block may be cast out of aluminum. However, aluminum cylinder blocks have several drawbacks, such as high friction coefficients and larger volume to strength ratios.
U.S. Pat. No. 5,370,087 discloses an engine having a composite cylinder case enclosing metal cylinder banks The inventors have recognized several disadvantages with the cylinder block disclosed in U.S. Pat. No. 5,370,087. Firstly, the cylinder case enclosing the cylinder banks is spaced away from the cylinder banks to enable coolant to flow around the cylinders. This type of arrangement decreases the structural integrity of the engine when compared to engines cast via a single continuous piece of metal. Therefore, forces transferred to the engine via external components such as the transmission may damage the cylinder case.
The inventors herein have recognized the above issues and developed an engine. The engine includes a thermal set composite cylinder block including a front engine cover attachment interface and a transmission attachment interface and a cylinder liner integrally molded with the composite cylinder block, the cylinder liner defining a portion of a boundary of a cylinder. The engine further includes a bulkhead insert extending through the thermal set composite cylinder block and is directly coupled to a cylinder head.
In this way, a composite material integrally molded with a cylinder liner and bulkhead insert may be used to form a portion of the engine to increase the engine's strength to weight ratio. Furthermore, the cylinder liner and bulkhead insert may comprise a metal or other suitable material having more desirable abrasion and heat transfer characteristics around the combustion chamber. In this way, selected portions of the cylinder block may be designed with different materials to increase the engine's strength to weight ratio without compromising desired combustion chamber characteristics. Moreover, integrally molding the cylinder liner and bulkhead insert with the cylinder block increases the coupling strength of the block assembly. Additionally, coupling the bulkhead insert direct to the cylinder head enables combustion loads travelling through the head bolts to be tied to reactive loads from the crankshaft bearing caps. As a result, loads are more evenly distributed throughout the engine, thereby increasing the engine's longevity.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.
FIGS. 2-3 are drawn approximately to scale, however other relative dimensions may be utilized if desired.